360 Crank in a 318?

[Road_Runner]

Lots of good feedback above, for me it will be a choice between keeping the main parts of the drivetrain 'mostly' stock with internal changes on one end to not worrying about it and just replace everything with whatever I want.  I'm just thinking the car has stayed unmolested for 40 years, I kind of hate to throw all that out making it a hotrod.  So mid-to-high 300's HP-wize out of the 318 will make it fun to drive on the street while leaving it looking as stock as possible.  So paying a little more keeping the original 318 to get where a barely warmed over 360 would get me makes sense since I'd rather keep the 318 in the car. 

Thanks again, Jim

[dodge freak 2]

"unmolested"..its a freaken car, not a person, lol

The car got "messed" up right from the factory due to EPA smog rules and limited technology 40 years ago. You are not messing up the car but making the car "better"

You really believe the factory would had used point dist 40 years ago if they had electronic ignitions back then ?   Plus their  high dollar Hemi cars were to be the "best".

Forget what the factory did 40 years ago, its 2012-soon to be 2013. I would try to make the car the "best" for today's world. You are improving the car-if done correctly

My car has lots of "old school" stuff but it also has a newer cam design and a MSD E curve dist with a MSD 7al box and HVC to fire the spark plugs to fully burn the A/F, that plus the newer technology torque converter and those MP cylinder heads is why I feel it runs well and consisted   

I might had used the 360 stroke crank throw but my 340 block had to go .040 over and I didn't feel comfortable increasing the stroke to 4 inches-not with the short deck height block so I just went with a .040 over 340 engine. My car came with a 318 but so what, the 340 does look the same and took all the same parts just about.

On paper the 400 engine seemed better but that meant different intake, exhaust, trans

I really not sure if the 360 engines do look any different-I don't see how but I had no 360 or 340 engine and found a 340 for $600-which needed an oversize lifter which I didn't know about and cost me $270 to bush the lifter bore-guess why the engine wasn't rebuilt years ago

Maybe I should had went with a 360 looking back but then again the motor work out well and its got a forged crank and seems balanced great-its smooth all the way. 340 pistons have a bit longer skirts then 360 pistons, means less rock at TDC and less piston speed at the same rpm   

[73restomod]

I checked again on allpar, and my old 70-74 manual, just to make sure that my numbers were right. Allpar list the 360's torque as 285 for the E-58 package. My manual list 275. The only mopar motor i found listed at 320 during or after 74 was the 440.

Sent from my DROID RAZR using Tapatalk 2

[Chryco Psycho]

72 up uses lower net HP ratings so the HP is down 30% from 70-71 #s

[73restomod]

True, but early 360s, from what I've been able to find, were only available as 2 barrels. One of these days, I need to find my old decoding magazine from Galen circa 94. So much good info in there. I don't want anyone to think I'm against stroking a motor. I'm not,  stroking a motor has nice side effects. Light piston and rod. The increased slug weight of the crank throw is has the effect of a heavier flywheel. The faster piston speed for a given rpm,  will increase port velocity (351 4V Cleveland vs. 302 4V Cleveland anyone?). However, a high velocity port (insert any mopar casting here, with the exception of the Max Wedges) with a short stroke motor, which is then stroked, will reach critical port speeds (about 400fps at the short side radius in a well designed port) much sooner. This causes power to drop off much earlier, and limits overall rpm. A Truck motor powerband is not sporty, nor very exciting to drive. The first part of a motor I think about is the heads I'd like to run. Then based on flow rates, I'll figure out the optimal displacement.

Sent from my DROID RAZR using Tapatalk 2

[dodge freak 2]

Pistons are lighter cause the skirts have to be shorter-that isn't a good thing, shorter skirts means more rock on tdc and that hurts ring seal.

I feel there is good reason those hot little V's Ford (302), Chevy(327) and Mopar(340) in 1970 used 3, 3.25 and 3.31 stroke. Rpm ruled, you geared for torque

The factory did not build BB engines with higher deck heights for more stroke for nothing, they knew the engines would not last as long with short piston skirts.

Now racing is another story, the factory was building every engine to last a long long time   

[73restomod]

I agree strokers have their disadvantages as well. I can't say I've seen factory long stroke motors last 350,000 miles like my fathers 72 318, which still runs like a top ( also a rare Canadian one with the single plane 2 bbl intake).

Sent from my DROID RAZR using Tapatalk 2

[bad440]

The E58 package in 1974(only year for this HP rating) was 245HP and 320 torque. This was the first year a 360 4 BBL was offered. In 1975 the E58 was offered but HP was down to 230. In later years the E58 was was watered down to 190 HP. AllPAR is incorrect if that is where you got those HP figures, nothing like being the original owner to this day for accuracy in these kind of details; further research will prove what I am saying here regarding 360 HP. Also in 1974 the 440 was rated at 275HP, 380 torque for comparison purposes. When catalytic converters became standard equipment for all engines in 1975 it was the end of an era.

[73restomod]

True, but the E-58 (interceptor) package had at least a half point more compression than the standard 4 barrel version or the 340; was more like 9.1. I know this because I have a set, side by side, its easy to see the chamber size difference. Half a point gives it at least a 2% advantage in power. Which makes the comparison more biased towards the 360. In the case of the 440, the standard (non-magnum) version numbers are what I've quoted for both motors. Using the E-58 package as the sole judging stick is like comparing a 340 to a 340 six pack. Anyway my point wasn't to argue ratings. If you divided the rated hp by cubic inches the 340 averages .72; the 360 averages .69. I'll do the torque as well, 290/340 is .87 per cube. 320/360 is .91. Now give the 340 2-3% to account for compression difference, and the gap closes to. 89-.9 on torque. If the 340 had the 360 hp/ci ratio it will drop to 234. If the 360 had the 340's hp/ci you end up with 260. Which brings me back to my point. The 360 was 20 cubes larger, had a piston that was 150 grams lighter, better compression, and everything else was the same; why does it eek out a marginal edge with all those win-wins. It points to an intake system tuned for a smaller motor size. It was insufficient to support a bigger motor. Especially a longer stroke motor that increases port velocities to the breaking point that much sooner.

Sent from my DROID RAZR using Tapatalk 2

[bad440]

All 360's from the 70's whether 2 BBl or 4 BBl used the same heads, the only difference between 340 heads and 340 sixpak was the offset pushrod location, there was no other difference as far as physical shape. THe compression on those engines was the same no matter what carburetion it came with. This info is easily verifiable by looking at a Mopar engine manual which will give casting numbers and combustion chamber volume. As a matter of fact the 340 six barrel used a 360 casting even though the 360 didn't come out till '71. What is an E58 interceptor package??

[73restomod]

Cop car 360s used a head with a smaller cc chamber. I have a set that I pulled from a 76 Diplomat (non egr). Next to a set of 73  J heads the difference is easily seen by eye, even after milling the J heads .030 there is still a measurable difference in size. Other designations of 4bbl 360s are E-54; E-55; and E 56..

here are some photos

I'll start with the 73J heads that have been shaved .030
This is the depth measurement on the flat if the chamber, followed by width and height.







Now for the cop car heads shaved .010 for a cleanup (years ago, never used because one head was craked)







I used the smallest chamber from the 73J's and the biggest from the Squad Car head.

Sent from my DROID RAZR using Tapatalk 2

[73restomod]

Another good comparison (that I should have made to begin with), would be between the 5.2L and the 5.9L magnums. In the 1997 model year the 5.2L made 230hp, the 5.9L made 245hp. Now the 5.9L enjoyed a larger camshaft (more duration), a bigger intake valve (1.92 vs. 1.94), a larger throttle body, and 42 cubic inches in displacement compared to the 5.2L; by all means if the intake system is equally effective on both, the 5.9L should have easily made 260hp, but it doesn't. When it comes to torque the 5.2L made 320 f.t lbs. versus the 5.9L's 345 ft. lbs.; that puts torque per ci. at 1.006 ft-lbs. per ci. for the 5.2, and the 5.9L works out to .958 ft-lbs. per ci. It just points to the fact that the 5.2L isn't taxing the intake system as hard. In effect it breathes easier, while the 5.9L might as well be trying to breath through a mild restrictor plate. Which is the point I was trying to make before I got side-tracked. Start with your intake flow, then try to figure out the best displacment for efficency versus raw size. Torque is purely a function of diplacement, combustion pressure, and intake flow; even then, every motor has an effective ceiling on torque. Getting as close to that peak as possible is mostly a matter of intake flow.

[dodge freak 2]

I would not pay so much attention how the factory rated the engines back then. You will not build it the same way, would you ?

Today you can easily get a higher compression 318 or 360 engine and you can use many different types of cylinder heads and camshafts. Pistons in higher compression are made by many manufactures.

So far my 340 Hyper pistons are holding up but I would feel more at ease if they were high dollar forged pistons.   

Compression, cam and heads can make or break an engine.  The factory built those smog engines to pass smog standards, not to make HP

[PlumCraZRT]

Another good comparison (that I should have made to begin with), would be between the 5.2L and the 5.9L magnums. In the 1997 model year the 5.2L made 230hp, the 5.9L made 245hp. Now the 5.9L enjoyed a larger camshaft (more duration), a bigger intake valve (1.92 vs. 1.94), a larger throttle body, and 42 cubic inches in displacement compared to the 5.2L; by all means if the intake system is equally effective on both, the 5.9L should have easily made 260hp, but it doesn't. When it comes to torque the 5.2L made 320 f.t lbs. versus the 5.9L's 345 ft. lbs.; that puts torque per ci. at 1.006 ft-lbs. per ci. for the 5.2, and the 5.9L works out to .958 ft-lbs. per ci. It just points to the fact that the 5.2L isn't taxing the intake system as hard. In effect it breathes easier, while the 5.9L might as well be trying to breath through a mild restrictor plate. Which is the point I was trying to make before I got side-tracked. Start with your intake flow, then try to figure out the best displacment for efficency versus raw size. Torque is purely a function of diplacement, combustion pressure, and intake flow; even then, every motor has an effective ceiling on torque. Getting as close to that peak as possible is mostly a matter of intake flow.

It's a well known fact that smaller engines are more efficient, but obviously the way to get more power is more displacement (or forced induction).  Larger displacements (with the same peak power) will yield flatter torque curves, better low end torque, better idle characteristics (better streetability), lower stall converter... basically an engine that is easier to manage.  I'm sure, you can get a 318 to make 400 hp with the right set of parts, but you're not gonna have fun driving that engine around town.  Certainly my 451 stroker, at 500 hp, will be a much easier engine to work with.

[73restomod]

I agree, a bigger motor is an easy way to get there. Not long ago I saw a stroked 410 ci small block mopar make about 310 at the rear wheels. Its an ok number, but they choked it to death with factory iron. If they had stepped up to better cylinder heads they probably could have gotten into the 340-350 range where a motor of that size should thrive. I've seen well built (not ridiculously cammed, ported factory headed) 383 big blocks get there without any drive ability issues.

Sent from my DROID RAZR using Tapatalk 2